Fork lift clamp

ABSTRACT

An adjustable pressure clamp adapted to mount above and between the tines of the fork of a fork lift truck whereby loads raised by the fork are secured thereon by the clamp. The clamp comprises a pressure plate joined to a slide which rides perpendicularly of the pressure plate in a channel provided for the purpose in a mounting bracket. The mounting bracket is provided with two Ushaped securing means which are oppositely disposed to oppositely engage structural cross-members of the fork lift assembly. The lower U-shaped securing means comprises an open channel while the upper U-shaped securing means comprises a sliding locking pin which permits removal of the clamp from the truck. Spring-loaded ratchet means are provided between the pressure plate and the mounting bracket to adjustably secure the pressure plate in any of a finite number of positions. The pressure plate is springurged to assist in release of loads.

United States Patent I191 Silva FORK LIFT CLAMP [75] Inventor: Joseph Silva, Richmond Hill, NY.

[73] Assignee: Saul Freier, Richmond Hill, NY. 22 Filed: Jan. 29, 1973 i [21] Appl. No.: 327,794

Primary Examiner-Robert G. Sheridan Assistant Examiner-George F. Abraham Attorney, Agent, or Firm-Stoll & Stoll Mar. 19, 1974 [5 7 ABSTRACT An adjustable pressure clamp adapted to mount above and between the tines of the fork of a fork lift truck whereby loads raised by the fork are secured thereon by the clamp. The clamp comprises a pressure plate joined to a slide which rides perpendicularly of the pressure plate in a channel provided for the purpose in a mounting bracket. The mounting bracket is provided with two U-shaped securing means which are oppositely disposed to oppositely engage structural crossmembers of the fork lift assembly. The lower U- shaped securing means comprises an open channel while the upper U-shapecl securing means comprises a sliding locking pin which permits removal of the clamp from the truck. Spring-loaded ratchet means are provided between the pressure plate and the mounting bracket to adjustably secure the pressure plate in any of a finite number of positions. The pressure plate is spring-urged to assist in release of loads.

6 Claims, 6 Drawing Figures Pmmmm 19 1914' 379758 T SHEEY 1 0F 2 n M 1 H 4 meme? PATENTEDIAR I 9 I974 SHEET 2 0F 2 I FORK LIFT CLAMP BACKGROUND OF THE INVENTION amount will tip even the most stable load since there is no positive means to retain the load on the fork.

Light loads or loads which are for some other reason inherently unstable have presented a tipping problem. An example which is of common experience to fork lift truckvoperators is the carryingof a high stack of empty pallets; Being a relatively 'light load, having a relatively high center of gravity and presenting a substantial wind load, it is a very ticklish matter to prevent the stack from tipping over.

SUMMARY OF THE INVENTION Accordingly, the present invention provides positive means forclamping a load onto'the fork of a fork lift truck.

The present invention further provides adjustable means for applying vertically downward pressure upon a load which is raised vertically upwardly by the fork of a fork lift truck.

The present invention also provides a removable clamp which may be conveniently positioned on the fork lift truck for use when necessary and may be readily removed when the shape or size of a load would interfere with the clamp.

The invention still further provides foot operated adjusting means for securing a load on the fork of a fork lift truck.

Briefly, but not by way of limitation, the present invention comprises a bracket which may be mounted on the structural cross-members which are present in conventional fork lift trucks. The cross-members extend across the tines of the fork and are lifted therewith. The present invention additionally provides vertical channel means in which rides the slide portion of a horizontal pressure plate. The pressure plate may be prevented from rising relative to the mounting bracket by means of a ratchet arrangement which is foot operated. Spring means are provided to assist in raising the pressure plate and slide when the ratchet is released.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a side view of the fork lift clamp of the present invention showing the pressure plate in a secondary 'position in phantom. The clamp is shown mounted on FIG. 5 is a cross-sectional view taken across line 5--5 of FIG. 2. The secondary position of the pressure plate shown in phantom in FIG. 1 is also shown in phantom in FIG. 5.

FIG. 6 is a perspectiveview of a conventional fork lift truck shown lifting an empty pallet. Securing the pallet onto the fork is a fork lift clamp of the present invention. It will be seen that the load is secured between the fork on the bottom and the clamp on the top.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Referring to the drawing, the fork lift clamp 10 of the present invention comprises a relatively planar pressure plate 12 which, when mounted as will be described on a fork lift truck 14, will be substantially horizontal. Upstanding substantially perpendicularly from an inner end 16 of pressure plate 12 is a slide 18 which is rigidly secured to pressure plate 12 by a web 20. Web 20 is a strengthening member extending between and joined integrally with pressure plate 12 and slide 18. Slide 18 is in effect a cross-plate which, in combination with web 20, forms a T-shape when viewed from above as shown in FIG. 3 wherein the slide is the top of the T. Slide 18 and pressure plate 12 meet'in a line which extends, as will be seen, laterally between the tines of the fork of fork lift truck 14.

A mounting bracket 22 comprises oppositely disposed parallel vertical sidewall members 24 and 26 respectively, securely joined by a vertical cross-member which is a vback plate 28. Inner opposite vertical grooves 30 and 32 are formed in sidewall members 24 and 26 respectively to conjointly form a channel 34 adapted to receive slide 18 for vertical movement therein.

The combination of sidewall members 24 and 26, back plate 28 and slide 18 forms a relatively rectangular enclosed way 36 in which is placed a lift spring 38 which bears between a lower spring seat 40, which is secured to back plate 28, and an upper spring seat 42, which is secured to slide 18. Lift spring 38 being a compression type spring, the tendency is for upper spring seat 42, and slide 18, web 20 and pressure plate 12 joined thereto, to be spring-urged upwardly relative to lower spring seat 40 and mounting bracket 22 joined thereto. Clearly, pressure plate 12 is adapted to move vertically upwardly and downwardly relative to mounting bracket 22 when the mounting bracket is secured vertically, such as on the fork lift truck.

It should here be stated that all directions mentioned herein are taken relative to the ground and to the position which fork lift clamp 10 assumes when mounted on a fork lift truck conventionally resting on the ground.

The rear of back plate 28, opposite way 36 and pressure plate 12, is provided with securing means 43 to removably secure fork lift clamp 10 to fork lift truck 14.

In conventional fork lift trucks there are structural members which run horizontally between the back sections 44 of forks 48. In many conventional fork lift trucks such members are major structural load bearing members and, being joined to the fork, move therewith. Although dimensions and number of such structural cross-members may vary from manufacturer to manufacturer, and perhaps from model to model, of fork lift trucks, variations are not all that great and it is within scope of the invention to adapt the securing means 43 to the varying dimensions of the cross-members. Shown by way of illustration in the drawing are two horizontal structural cross-members 50 disposed vertically, one above the other.

It is the purpose of securing means 43 to rigidly and removably secure fork lift clamp to structural crossmembers 50. Securing means 43 comprises a lower upwardly opening U-shaped channel 52 formed by back plate 28 and an L-shaped member 54 secured thereto. U-shaped channel 52 is adapted to receive the lower of structural cross-members 50.

The upper of securing means 43 comprises a springurged retractable locking pin 56 secured in parallel spaced relation to back plate 28 by a frame 58. Frame 58 has upper and lower horizontal sections 60 each provided with a through hole to vertically receive locking pin 56. Bearing between the upper of horizontal sections 60 and a cross pin 62 is a spring 64 which urges I locking pin 56 downwardly to project below frame 58 a sufficient amount to engage the upper of structural cross-members 50 and secure the same between it and back plate 28. Locking pin 56 may be manually withdrawn in a vertically upwardly direction so as to release the upper of structural cross-members 50 and permit removal of fork lift clamp 10 from fork lift truck 14. A handle 61 is provided on locking pin 56 for convenience. The bottom edge of locking pin 56 may be provided with a rearwardly facing tapered surface 66 to permit automatic retraction of locking pin 56 by cam action against the upper of structural cross-members 50 to permit convenient placement of clamp 10 on truck 14 without additionally requiring manual retraction of locking pin 56.

The forward edge of sidewall member 24 is provided with a plurality of downwardly facing ratchet teeth 68 which is engaged by a spring-urged pawl 70 which is mounted on web 20. The combination of pawl 70 on web and ratchet 68 on sidewall member 24 is such as to lock pressure plate 12 against vertical upward movement relative to mounting bracket 22 at any of a number of desired positions. Vertical downward movement of pressure plate 12 is permitted by ratchet 68 but upward movement requires release of pawl 70 from the ratchet. Pawl 70 is provided with an enlarged handle 72 which is adapted to be engaged by a foot to release the pawl from the ratchet.

As may be seen in FIG. 6, clamp 10 of the present invention secures a load by applying downward pressure to the load which is resisted by the upward pressure of fork 48. With sufficient pressure as determined by the vertical position of pressure plate 12, the load is effectively secured to the fork lift and will not be disturbed therefrom.

While the foregoing is illustrative of a preferred embodiment of the invention it is clear that there are other embodiments and modifications which may be had within the broad teaching hereof.

What is claimed is:

l. A clamp for mounting on a fork lift truck, comprising:

a. a mounting bracket;

b. securing means, said securing means securing said mounting bracket to the fork lift truck and comprising a lower U-shaped channel and upper locking pin means, said U-shaped channel being formed by said mounting bracket and an L-shaped member secured thereto, said upper locking pin means comprising a locking pin retractably held by a frame which is secured to said mounting bracket, whereby said securing means engages structural members on the fork lift truck;

c. pressure plate means, said pressure plate means being vertically slidably engaged with said mounting bracket; and

d. positioning means, said positioning means positioning said pressure plate means with respect to said mounting bracket.

2. A clamp for mounting on a fork lift truck in accordance with claim 1, wherein:

a. said pressure plate means comprises a substantially planar pressure plate, and a slide upstanding from said pressure plate;

b. said slide being engaged by said mounting bracket for vertical movement relative thereto.

3. A clamp for mounting on a fork lift truck in accordance with claim 2, wherein:

a. said mounting bracket comprises a pair of oppositely disposed vertically extending sidewall members and a back plate secured between said sidewall members;

b. said sidewall members having oppositely disposed grooves formed therein to define a channel which slidably receives said slide, said slide in combination with said sidewall members and said back plate defining a longitudinally extending way.

4. A clamp for mounting on a fork lift truck in accordance with claim 3, wherein:

a. said way is provided with two spring seats, a first spring seat being secured to said back plate and a second spring seat being secured to said slide;

b. a spring, said spring acting between said seats whereby said slide is spring-urged relative to said mounting bracket.

5. A clamp for mounting on a fork lift truck in accordance with claim 3, wherein:

at least one of said vertically extending sidewall members is provided with a ratchet.

6. A clamp for mounting on a fork lift truck in accordance with claim 5, wherein:

said positioning means being mounted on said pressure plate means and comprising a pawl engageable with said ratchet. 

1. A clamp for mounting on a fork lift truck, comprising: a. a mounting bracket; b. securing means, said securing means securing said mounting bracket to the fork lift truck and comprising a lower U-shaped channel and upper locking pin means, said U-shaped channel being formed by said mounting bracket and an L-shaped member secured thereto, said upper locking pin means comprising a locking pin retractably held by a frame which is secured to said mounting bracket, whereby said securing means engages structural members on the fork lift truck; c. pressure plate means, said pressure plate means being vertically slidably engaged with said mounting bracket; and d. positioning means, said positioning means positioning said pressure plate means with respect to said mounting bracket.
 2. A clamp for mounting on a fork lift truck in accordance with claim 1, wherein: a. said pressure plate means comprises a substantially planar pressure plate, and a slide upstanding from said pressure plate; b. said slide being engaged by said mounting bracket for vertical movement relative thereto.
 3. A clamp for mounting on a fork lift truck in accordance with claim 2, wherein: a. said mounting bracket comprises a pair of oppositely disposed vertically extending sidewall members and a bacK plate secured between said sidewall members; b. said sidewall members having oppositely disposed grooves formed therein to define a channel which slidably receives said slide, said slide in combination with said sidewall members and said back plate defining a longitudinally extending way.
 4. A clamp for mounting on a fork lift truck in accordance with claim 3, wherein: a. said way is provided with two spring seats, a first spring seat being secured to said back plate and a second spring seat being secured to said slide; b. a spring, said spring acting between said seats whereby said slide is spring-urged relative to said mounting bracket.
 5. A clamp for mounting on a fork lift truck in accordance with claim 3, wherein: at least one of said vertically extending sidewall members is provided with a ratchet.
 6. A clamp for mounting on a fork lift truck in accordance with claim 5, wherein: said positioning means being mounted on said pressure plate means and comprising a pawl engageable with said ratchet. 